India´s government warned health and wildlife officials throughout the country to watch for symptoms of avian influenza among migratory birds that have begun arriving from China and other regions affected by the disease.

Avian flu can spread to humans through poultry that come into contact with wild birds, and authorities are taking blood samples from poultry stocks close to the about 50 bird sanctuaries in the country, said P. M. A. Hakeem, a senior Indian official who monitors farm animals and fisheries.

"There is a small possibility that some of the birds that come from certain regions could be carrying the virus," he said. "So far, we haven´t come across the virus, but we are watching."

A number of species of birds, especially waterfowl, winter in India, attracted by its tropical weather.

Migratory birds were not thought to be prone to bird flu until an outbreak was detected earlier this year in bar-headed geese at a saltwater lake in Qinghai, China - a breeding site for birds that spend the winter in Southeast Asia, Tibet and India. The virus also infected brown-headed gulls and great black-headed gulls.

Six or seven pairs of bar-headed geese were sighted last week near the Cauvery river in the southern Indian state of Karnataka, marking their arrival this season, said a forestry official, Prasanna Kumar.

"We can´t really disturb the birds and test if they have flu, but if they do, we will make sure it doesn´t spread to poultry or humans," said Kumar, who works at the Ranganathittu bird sanctuary, 140 kilometres south of Bangalore.